我正在尝试创建一个多边形区域以选择散点图上的点。问题是我不知道如何在散点图上映射鼠标位置。
我使用mapFromDevice，但是结果不令人满意，因为位置是圆形的并且不精确（我猜这是因为它适应散点图坐标系）。
我不知道我使用的是不好的方法。
from PyQt5 import QtGui
from PyQt5.QtWidgets import *
from PyQt5 import QtCore
import pyqtgraph as pg
import sys
class MVAQPlot(QWidget):
def __init__(self):
QWidget.__init__(self)
self.resize(600,600)
pg.setConfigOption('background', 'w')
pg.setConfigOption('foreground', 'k')
self._graphics_layout = pg.GraphicsLayoutWidget(self)
layout = QHBoxLayout()
layout.addWidget(self._graphics_layout)
self.setLayout(layout)
self._scores = ([1, 1.5, 3, 5, 5], [1, 1.5, 3.4, 4, 2])
self._roi = pg.PolyLineROI([], pen=(5))
self._scatter_plot = pg.ScatterPlotItem()
self._scatter_plot.setData(self._scores[0], self._scores[1])
plot = self._graphics_layout.addPlot()
plot.addItem(self._scatter_plot)
plot.addItem(self._roi)
self._selection_timer = QtCore.QTimer()
self._selection_timer.timeout.connect(self.update_selection)
self._creating_region = False
self._last_point = None
def mousePressEvent(self, event):
if event.button() == QtCore.Qt.LeftButton:
if self._creating_region:
self._creating_region = False
self._selection_timer.stop()
roi_shape = self._roi.mapToItem(self._scatter_plot, self._roi.shape())
self._points = list()
for i in range(len(self._scores[0])):
self._points.append(QtCore.QPoint(self._scores[0][i], self._scores[1][i]))
selected = [roi_shape.contains(pt) for pt in self._points]
print('Selected points: ' + str(selected))
self._roi.clearPoints()
else:
self._creating_region = True
self._selection_points = list()
self._selection_timer.start(1000)
def update_selection(self):
if self._roi is not None:
point = QtCore.QPoint(self._graphics_layout.lastMousePos[0],
self._graphics_layout.lastMousePos[1])
self._selection_points.append(point)
region = QtGui.QPolygon(self._selection_points)
mapped_point = self._scatter_plot.mapFromDevice(region)
self._roi.setPoints(mapped_point)
if __name__ == '__main__':
app = QApplication(sys.argv)
widget = MVAQPlot()
widget.show()
sys.exit(app.exec_())
我不知道如何在散点图上绘制精确的PolyLineROI。像这样：
最佳答案
问题是您使用的QPoint和QPolygon仅支持整数，如果传递浮点数，则将其四舍五入。解决方案是使用QPointF和QPolygonF：
def update_selection(self):
if self._roi is not None:
point = QtCore.QPointF(
self._graphics_layout.lastMousePos[0],
self._graphics_layout.lastMousePos[1],
)
self._selection_points.append(point)
region = QtGui.QPolygonF(self._selection_points)
mapped_point = self._scatter_plot.mapFromDevice(region)
self._roi.setPoints(mapped_point)
关于python - 如何在散点图上绘制鼠标位置？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/57719303/